Insight into the high temperature performances of alumina foams

Understanding the causal relations between the load situation and the lifetime at high temperature is extremely important in the application of alumina foams in high temperature industry. In this work, alumina foams were obtained at the sintering temperature of 1700 °C. The observation of microstructure of alumina foams showed that the structure of grains in the pore wall were of point contact structure. Key properties, such as flexural strength, elastic modulus, compressive creep, coefficient of thermal expansion and thermal conductivity of alumina foams were measured from room temperature to 1400 °C. The variation of the above properties of alumina foams as a function of temperature was investigated. The results showed that significant decrease in flexural strength and elastic modulus were observed when the temperature was over 1000 °C. Under this unique structure, minor liquid phase at the grain boundary could lead to the grain slip and further the remarkable decreases of the high temperature performance.